Process to produce novel fluorocarbon vinyl ethers and resulting polymers

ABSTRACT

Novel vinyl ethers are prepared in decarboxylation reactions of novel acid fluoride compounds according to the following reaction: ##STR1## wherein a is 0 or an integer greater than 0; 
     b is 0 or an integer greater than 0; 
     n=1 or an integer greater than 1; 
     R f  and R f   &#39;  are independently selected from the group consisting of F, Cl, perfluoroalkyl or fluorochloroalkyl; 
     X=F, Cl, Br or mixtures thereof when n&gt;1 
     X&#39;=Cl or Br; 
     Y is an acid group or an acid derivative easily convertible to an acid group; 
     Z=F, Cl, Br, OH, NRR&#39; or OA; 
     R and R&#39; are independently selected from the group consisting of hydrogen, an alkyl having one or more than one carbon atoms, and aryl; and 
     A=alkali metal, quaternary nitrogen, or R. 
     These vinyl ethers may be homopolymerized with themselves or copolymerized with other vinyl ethers.

This is a divisional of application Ser. No. 345,894, filed Feb. 4,1982.

BACKGROUND OF THE INVENTION

U.S. Pat. No. 3,282,875 shows the following decarboxylation reaction##STR2## where

R_(f) is F or a perfluoroalkyl radical having from 1-10 carbon atoms;

y is F or trifluoromethyl radical;

n is an integer of 1-3, inclusive;

M is F, hydroxyl radical, amino radical or OMe; and

Me is an alkali metal or a quaternary nitrogen radical.

Yields in the decarboxylation reaction of about 80% were obtained athigh temperatures (about 300° C.) while yields of 20-30% were obtainedat lower temperatures (about 200° C.). Also taught is the homo andcopolymerization of the vinylether monomers to form useful polymers.

British Pat. No. 1,518,387 teaches the following reactions ##STR3##

Copolymers of the vinylether monomers with tetrafluoroethylene wereshown to be useful as membranes in chlor-alkali electrolytic cells.

Fearn, et al. Journal of Polymer Science, Volume 4, pp. 131-140,"Polymers and Terpolymers of Perfluoro-1,4-pentadiene" discloses that inthe pyrolysis of sodium salts of carboxylic acids which contain fluorineand chlorine in the β position, sodium chloride is preferentially, butnot exclusively eliminated. For example ##STR4##

German Pat. No. 1,238,458 teaches that useful polymers are made fromcompounds of the general structure ##STR5## where n=1-8, p=0-5.Crosslinked halogenated olefin copolymers are produced making use of theiodine group as a reactive site.

R. D. Chambers, in his book, Fluorine in Organic Chemistry, published byJohn Wiley & Sons, 1973, pages 211-212, teaches that carboxylic acidderivatives may be converted to olefins. The conversion is taught toinvolve the loss of carbon dioxide and formation of an intermediatecarbanion. The intermediate then looses NaF to form the resultingolefin.

Numerous patents and publications have taught the use of acid functionalfluorocarbon polymers in chlor-alkali electrolytic cells (British Pat.Nos. 1,497,748; 1,497,749; 1,518,387 and U.S. Pat. Nos. 3,784,399;3,969,285; 4,025,405).

BRIEF DESCRIPTION

Novel compounds are prepared by decarboxylation of carboxylic acidderivatives according to the following reaction: ##STR6## where

a=0 or an integer greater than 0

b=0 or an integer greater than 0

n=1 or an integer greater than 1;

R_(f) and R_(f) ' are independently selected from the group consistingof F, Cl, perfluoroalkyl or fluorochloroalkyl;

X=F, Cl, Br or mixtures thereof when n>1

X'=Cl or Br;

Y is an acid group or an acid derivative easily converted to an acidgroup;

Z=F, Cl, Br, OH, NRR' or OA;

R and R' are independently selected from the group consisting ofhydrogen, an alkyl having one or more than one carbon atoms, and aryl;and

A=alkali metal, quaternary nitrogen, or R.

These vinyl ethers may be homo polymerized with them selves orcopolymerized with other vinyl ethers.

DETAILED DESCRIPTION

Novel compounds are prepared by decarboxylation of carboxylic acidderivatives according to the following reaction: ##STR7## wherein

a is 0 or an integer greater than 0;

b is 0 or an integer greater than 0;

n is one or an integer greater than one;

R_(f) ' and R_(f) =are independently selected from the group consistingof F, Cl, perfluoroalkyl and fluorochloroalkyl;

X=F, Cl, Br or mixtures thereof when n>1;

X'=Cl or Br;

Y is an acid group or an acid derivative easily convertible to an acidgroup.

Z=F, Cl, Br, OH, NRR' or OA;

R and R'=are independently selected from the group consisting ofhydrogen, an alkyl having one or more than one carbon atoms, and aryl;and

A=alkali metal, quaternary nitrogen, or R.

A variety of conditions usually involving a base are generally used forthe decarboxylation reaction. Direct reaction of the above compoundwhere Z=F with sodium carbonate as a slurry in a solvent such as glyme,diglyme or tetraglyme is particularly simple. Other methods arepyrolysis of the compound where Z=OH or ONa and reaction of the Z=Fcompounds with hot K₂ SO₄ or Na₂ SO₄ or pyrolysis with ZnO or Silica.Water alone converts the compound directly to the carboxylic acid whichcan be pyrolyzed. It is generally accepted that conversion of carboxylicacids or derivatives to olefins involves loss of carbon dioxide to forman intermediate carbanion. In the present case producing the followingreactive intermediate ##STR8## This reactive intermediate then losesNaX' to form the resulting olefin (monomer). At this point it is alsopossible to lose NaF which would result in formation of a X'(Cl, Br)substituted olefin, i.e., ##STR9## While it is not particularlysurprising that loss of NaX' predominates, it is surprising that loss ofNaX' as opposed to NaF is the sole detected course of the reaction,particularly when X'=Cl. Loss of NaF, while not being favored over lossof NaX', does readily occur from similar carbanion intermediates (U.S.Pat. No. 3,282,875). Indeed, Fearn discloses that in the decarboxylationof the structure shown below, elimination of NaCl predominates, but isnot exclusive. ##STR10## Analysis of the vinyl ethers produced by thepresent invention by VPC, I.R., mass spectrocopy and F 19 NMR failed todetected the presence of any ˜OCF=CFCl.

The above discussion describes a theory as to how the reactions proceedbut in no way limits nor defines the scope of the invention.

Y is an acid group or an acid derivative easily convertible to an acidgroup. Y may be SO₂ --Z, ##STR11## or C.tbd.N or other appropriategroups groups. (As Z is defined above).

When polymers made from the vinyl ether monomers of the presentinvention are to be formed into sheets for use as membranes, such as inchlor-alkali cells, it is desirable to choose Z so that the polymersformed are thermoplastic to allow fabrication by conventional means,such as melt extrusion, but after fabrication can be easily converted tothe acid or alkali metal salt of the acid. As an example, when Y=SO₂ F(Z=F), the intermediate is converted to an olefin monomer still havingthe --SO₂ F groups. The monomer is in turn copolymerized to form apolymer containing the SO₂ F group that can be formed into sheets byvarious plastic fabrication techniques. After fabrication, the SO₂ Fgroup is easily converted to the alkali metal salt of the correspondingsulfonic acid, --SO₂ ONa (Z=ONa), which can be converted to the sulfonicacid, --SO₂ OH (Z=OH), by reaction with acids, such as mineral acids.##STR12##

When Y is chosen as --C.tbd.N, a nitrile, the above conditions are metsince it is well known that nitriles are converted to carboxylic acidsby hydrolysis.

When the polymers derived from the present monomer intermediates are tobe used in particle or powder form, such as for acid catalyst, it is notcritical in the choice of Z since fabrication is not as large a factor.In this case, Z can conveniently be any of the radicals listed. It canbe --OH so as to directly have Y as an acid group or it can be any grouprendering Y convertible to an acid group by further reaction.

The radical X is chosen from the halogens Cl, Br or F, while X' ischosen from Cl or Br. While iodine would also be a useful radical for Xor X', formation of the ethers by the chemistry taught herein ishampered by side reactions causing low or nonexistant yields to thedesired compounds.

When X'=Cl or Br and X=F, Cl or Br, new uses and novel and surprisingnew chemistry results from using the intermediates for additionalchemical reactions. The prior art teaches that when Y=SO₂ F, n=0 andX'=F (U.S. Pat. No. 3,560,568) reaction of the intermediate with basedoes not produce the desired vinyl ether monomer, but rather a cyclicsulfone compound. Surprisingly, when n=0, Y=SO₂ F and X'=Cl or Br,reaction of the intermediate with base produces the desired vinyl etherproduct in one step. In addition to this benefit, choosing X'=Cl or Brand X=Cl or Br in compounds when n>0 results in introducing a potentialreaction site into polymers ultimately derived from monomers made fromthese intermediates. When n>0 both an acid site for ion exchange orcatalyst and a reaction site for further reaction can be obtained byhaving X=Cl or Br and making a copolymer or homopolymer of the vinylether. It is known that fluorocarbons having Cl or Br groups undergometallation reactions to produce reactive intermediates. On the otherhand, it is known that these substituents, particularly Cl, do notreadily enter into reaction with nucleophiles. Thus the products wouldbe unaffected in normal uses.

There is distinct benefit for having X'=Cl or Br. It is helpful to haveCl or Br in this position for the decarboxylation reaction. Indecarboxylations of the prior art, compounds of the terminalfunctionality shown below are common. ##STR13##

These materials generally require high temperatures and activators suchas ZnO or silica to achieve reasonable yields to desired vinyl ethers.##STR14##

When X'=Cl or Br in the present invention, decarboxylation of theseintermediates to vinyl ethers has been found to proceed under mildconditions and in excellent yields.

The variables have the following preferred values: n=1-6, a=0-3 andb=0-3. Even more preferred are compounds in which n=1-3. X is preferablyCl or X' is preferably Cl. R_(f) and R_(f) ' are preferably F. Y ispreferably Z'SO₂ and even more preferably Y=Z'SO₂ and Z'=F.

In general, the polymerization procedures and techniques followed in thepresent invention are known. A very good reference for polymerizationtechniques is Emulsion Polymerization--Theory and Practice, by D. C.Blackley, published by John Wiley & Sons.

Additionally, the copolymers used in the present invention may beprepared by general polymerization techniques developed for homo- andcopolymerizations of fluorinated ethylenes, particularly those employedfor tetrafluoroethylene which are described in the literature.Nonaqueous techniques for preparing the copolymers of the presentinvention include that of U.S. Pat. No. 3,041,317, to H. H. Gibbs, etal, that is by the polymerization of a mixture of the major monomertherein, such as tetrafluoroethylene, and a fluorinated ethylenecontaining sulfonyl fluoride in the presence of a free radicalinitiator, preferably a perfluorocarbon peroxide or azo compound, at atemperature in the range 0°-200° C. and at pressures in the range 1-200,or more atmospheres. The nonaqueous polymerization may, if desired, becarried out in the presence of a fluorinated solvent. Suitablefluorinated solvents are inert, liquid, perfluorinated hydrocarbons,such as perfluoromethylcyclohexane, perfluorodimethylcyclobutane,perfluorooctane, perfluorobenzene and the like.

Aqueous techniques which may also be used for preparing the copolymersused in this invention include contacting the monomers with an aqueousmedium containing a free-radical initiator to obtain a slurry of polymerparticles in non-waterwet or granular form, as disclosed in U.S. Pat.No. 2,393,967 to Brubaker or contacting the monomers with an aqueousmedium containing both a free-radical initiator and a technologicallyinactive dispersing agent, to obtain an aqueous colloidal dispersion ofpolymer particles and coagulating the dispersion, as disclosed, forexample, in U.S. Pat. No. 2,559,752 to Berry and U.S. Pat. No. 2,593,583to Lontz.

Any one monomer represented by the general formula may behomopolymerized with itself or any one monomer may be copolymerized withany other monomer represented by the general formula. Additionally, morethan two kinds of monomers represented by the general formula may bepolymerized.

In addition, any one or more of the monomers represented by the generalformula may be copolymerized, with any one or more of the monomersselected from the group consisting of tetrafluoroethylene,trifluoromonochlorethylene, trifluoroethylene, vinylidene fluoride,1,1-difluoro-2,2-dichloroethylene, 1,1-difluoro-2-chloroethylene,hexafluoropropylene, 1,1,1,3,3-pentafluoropropylene,octafluoroisobutylene ethylene, vinyl chloride, trifluoronitrosomethane,perfluoronitrosoethane and alkyl vinyl ether.

EXAMPLE 1

50 ml of dry tetraglyme and 8.0 grams anhydrous Na₂ CO₃ were added to a100 ml three-neck flask equipped with a stirrer, reflux condenser,thermometer, and a dropping funnel. Cold traps were located downstreamof the reflux condenser. 35.67 grams of an acid fluoride product wasanalyzed and found to contain:

    ______________________________________                                        Percent                                                                       (wt.)  Compound                                                               ______________________________________                                        12.8                                                                                  ##STR15##                                                             57.4                                                                                  ##STR16##                                                             6.82                                                                                  ##STR17##                                                             ______________________________________                                    

It was added then dropwise over a three-hour period to the flask. Thetemperature rose slightly from room temperature to about 35° C. AfterCO₂ evolution ceased, a 30 inch vacuum was pulled on the system and thereactor was heated slowly until the pot reached 143° C. and the overheadtemperature reached 99° C., 25.99 grams of product were collected. VPCanalysis gave the following results:

    ______________________________________                                        Percent                                                                       (wt.)   Compound                                                              ______________________________________                                        17.4    FSO.sub.2(CF.sub.2).sub.2OCFCF.sub.2                                  62.6                                                                                   ##STR18##                                                             2.4                                                                                   ##STR19##                                                            ______________________________________                                    

EXAMPLE 2

A 28 gram sample having the following mixture of acid fluorides

    ______________________________________                                        Parts                                                                         (wt.) Compound                                                                ______________________________________                                               ##STR20##                                                              26                                                                                   ##STR21##                                                              2.5                                                                                  ##STR22##                                                              2                                                                                    ##STR23##                                                              ______________________________________                                    

was added dropwise to a slurry of 100 ml of freshly distilled tetraglymeand 5 grams Na₂ CO₃ at 25° C. The mixture was stirred for one hour andthen heat was applied slowly. At approximately 80° C., evolution of gaswas observed. The products were collected by means of an ordinaryClaisen still head with a side arm condenser and a receiver packed indry ice on the side arm. A nitrogen purge was applied to excludemoisture initially. After gas evolution slowed at 95° C., the receiverwas exchanged, a 28 inch Hg vacuum was applied and the temperature wasraised to 135° C. for one hour. Collection was stopped and the twofractions analyzed. Fraction one had 13.75 grams analyzing as

    ______________________________________                                        Parts                                                                         (wt.)  Compound                                                               ______________________________________                                        1.7    FSO.sub.2(CF.sub.2).sub.2OCFCF.sub.2                                   21.7                                                                                  ##STR24##                                                                     ##STR25##                                                             ______________________________________                                    

Fraction two had 4 grams which was analyzed to be of the followingcomposition:

    ______________________________________                                        Parts                                                                         (wt.)  Compounds                                                              ______________________________________                                        3.8                                                                                   ##STR26##                                                                     ##STR27##                                                             1                                                                                     ##STR28##                                                             ______________________________________                                    

EXAMPLE 3

15 ml of tetraglyme and 1.0 gm of anhydrous Na₂ CO₃ were added to a 3neck flask equipped with a thermometer, stirrer and reflux condenser.Cold traps (-78° C.) were downstream of the condenser and a slightbackpressure of N₂ was maintained by means of a bubbler. FSO₂ CF₂ CF₂OCF(CF₃)CF₂ OCF(CF₂ Cl)CFO(3 gms) was added and after a brief evolutionof CO₂, the temperature was raised to 80° C. and held there for severalhours until CO₂ evolution ceased. A vacuum was pulled on the reactor andthe temperature was slowly increased to 136° C. while collecting 1.5 gmsof product in the cold trap. The majority of the product was collectedbefore the temperature reached 90° C. VPC analysis showed additionalproduct remaining in the tetraglyme solvent. The product, was confirmedas ##STR29## by Mass Spectrocopy, I.R. and F¹⁹ NMR.

Using the procedures of the foregoing examples, the following functionalfluorovinyl ethers are prepared: ##STR30##

EXAMPLE 4 ##STR31## and tetrafluoroethylene were polymerized together asfollows:

Ten grams of a mixture of FSO₂ --(CF₂)₂ --O--CF═CF₂ and ##STR32## wereadded to 400 ml of a deoxygenated water solution containing 3 g K₂ S₂O₈, 0.75 g NaHSO₃, 1.5 g Na₂ HPO₄, and 3.5 g C₇ F₁₅ CO₂ K soap in aglass-lined autoclave. The reaction was then carried out by maintaininga 60 psi tetrafluoroethylene pressure on the reactor for 16 hours withstirring at 10° C. The reactor was then vented, heated to 50° C. andevacuated to remove residual monomer. The contents were then frozen tocoagulate the polymer which was filtered and rigorously washed afterthawing. The dried polymer weighed 27.5 g. A film pressed from thepolymer exhibited bands in the infrared absorption region associatedwith the --SO₂ F group at 820 and 1465 cm⁻¹.

EXAMPLE 5

10 g of a mixture containing approximately two parts ##STR33## stirredstainless steel reactor containing 3 g K₂ S₂ O₈, 0.75 g NaHSO₂, 1.5 gNa₂ HPO₄, and 3.5 g C₇ F₁₅ CO₂ K. A 60 psi pressure oftetrafluoroethylene was then applied to the reactor and the temperaturemaintained at 20° C. for 13/4 hours. The reactor was vented, vacuumapplied and heated to 50° C. to remove volatiles. The contents were thenfrozen, thawed and filtered followed by vigorous washing to removeinorganics and soap. The vacuum dried polymer weighed 7 g. Titration ofa sample of the polymer, after hydrolysis from the --SO₂ --F to the SO₂--ONa form using NaOH in a ethanol water mixture, gave a value of 3409for the equivalent weight.

EXAMPLE 6

9.25 g of ##STR34## were added to 30 ml of ClCF₂ --CCl₂ F in a 100 mlstainless steel reactor. The contents were cooled to the freezing pointand 2 drops of 2-tert. butylazo-2-cyano-4-methoxyl-4-methylpentaneinitiator solution added. The reactor was then evaporated and 8 g oftetrafluoroethylene added by condensation. The reactor was heated to 50°C. and shaken for 14 hours. The reactor was then vented and the solventevaporated leaving a dried polymer residue of 4 g. The polymer wasanalyzed as containing 0.8% sulfur.

EXAMPLE 7

4.5 g of ##STR35## were added to 30 ml of ClCF₂ --CFCl₂ in a 100 mlstainless steel reactor. The contents were cooled to the freezing point,2 drops of 2-tert. butylazo-2-cyano-4-methoxyl-4-methylpentane initiatorsolution were added. The reactor was then evacuated and 8.25 gtetrafluoroethylene added by condensation. The reactor was then heatedto 50° C. and shaken for 22 hours. The reactor was vented and thesolvent evaporated, leaving a dried polymer residue of 7 g whichanalyzed as containing 0.6% sulfur.

We claim:
 1. A method of producing compounds of the formula: ##STR36##which comprises decarboxylating compounds of the formula: ##STR37## inthe presence of a base or an activator at a temperature and for a timesufficient to form said compound; whereinn=1; X'=Cl; X=Cl a=0 or aninteger greater than 0; b=0 or an integer greater than 0; Y is selectedfrom the group consisting of Z'SO₂, ##STR38## and C.tbd.N; R_(f) andR'_(f) are independently selected from the group consisting of F, Cl, aperfluoroalkyl radical and a chlorofluoroalkyl radical; Z' is F, Cl, Br,OH, NRR' or OA; R and R' are independently selected from the groupconsisting of hydrogen, an alkyl having one or more carbon atoms and anaryl; A is an alkali metal, quaternary nitrogen radical, or R.
 2. Themethod of claim 1 where a=0-3; b=0-3; R_(f) =F or Cl; and R_(f) '=F orCl.
 3. The method of claim 1 wherein the activator is selected from thegroup consisting of K₂ SO₄, Na₂ SO₄, ZnO, silica and water.